1. Field of Industrial Application
This invention relates to an adsorbent used for the purpose of separation--recovery of high purity CO from any mixed gas containing CO by the method of pressure swing adsorption (hereinafter referred to as PSA) and/or temperature swing adsorption (hereinafter referred to as TSA) and further, pertains to a method of preparing this adsorbent and the process for separation--recovery of high purity CO, using this adsorbent.
2. Prior Art
Representatives of gases with CO as their main component include converter gas obtained from converters in ironworks, blast furnace gas obtained from blast furnaces, electric furnace gas obtained from electric furnaces and producer gas obtained by gasifying coke. Most of these gases use for fuel. They contain around 70% by volume or more of CO, if the CO contained in these gases can be separated or recovered at high purities, it may be utilized as material for synthesizing formic acid, acetic acid, etc., or for reduction of organic compounds, etc., to be of great benefit to chemical industries.
Heretofore, as a process for separation--recovery of CO from gases with CO as their main component, there have been known low-temperature processing, cuprous ammonium processes, COSORB process, etc. These processes involve such problems as high cost for equipment and high expenses required for electric power, steam and the like heat energies, so that although they are suitable for separation--recovery of large volumes of CO, they are not necessarily adaptable for separation--recovery of medium or small volumes of CO. Moreover, because of the inclusion of the CO obtained through separation by these methods of such gases as O.sub.2, CO.sub.2, etc., which are deleterious to reactions of organic syntheses, it can not be put to use for organic syntheses.
As methods for making selective separation of specified gases from medium or small volumes of material gases, PSA and TSA methods are known.
The PSA method is one of methods for selective separation of the specified gas from any mixed gas, which effects separation of adsorbate from nonadsorbate by getting the object gas adsorbed on some adsorbent under a high pressure and then, removing the adsorbed object therefrom under a reduced pressure. In industrial applications, a plurality of towers filled with adsorbent are installed; in each adsorption tower, a series of operations of pressure-up--adsorption--cleaning--degassing are repeated, whereby the separation--recovery is continuously performed in the system as a whole.
The TSA method, like the aforementioned PSA method, is one of the methods of making selective separation of the specified gas from any mixed gas; the object gas is adsorbed on the adsorbent and then, by raising the temperature of the adsorption system, the adsorbate on the adsorbent is removed, thereby separating an adsorbate from nonadsorbates.
Heretofore, as a process for separation--recovery of CO from any mixed gas containing CO by this PSA method, a method utilizing mordenitic zeolite as the adsorbent has been proposed. (Refer to Japanese Patent Un-Examined Publication No. 22625/1984; ibid. No. 49818/1984.)
As a process for separation--recovery of CO from any mixed gas containing CO by the PSA or TSA method, use of such copper compounds as cuprous halides, cuprous oxide, cupric salts, cupric oxide, etc., carried on active carbon as the adsorbents has been proposed. (Refer to Japanese Patent Un-Examined Publication Nos. 156517/1983, 69414/1984, 105841/1984 and 136134/1984.)
As a preparing method of CO adsorbent--remover for use in separation--recovery of CO from any mixed gas containing CO by the PSA or TSA method, there has been proposed a process which comprises contacting an organic solvent solution of cuprous halides and aluminum halides with such a porous inorganic oxide(s) as alumina, silica or silica/alumina, etc., and then, removing free organic solvent. (Refer to Japanese Patent Un-Examined Publication Nos. 90036/1985 and 90037/1985.)
The applicant of the present invention has already filed an Japanese patent application for a method which comprises using an adsorbent for separation--recovery of CO composed of a carrier formed of silica and/or alumina on which cuprous or cupric compound or the latter's reduction products are carried as a process for separation--recovery of CO from any mixed gas containing CO by the PSA or TSA method. (Japanese Patent Application No. 82978/1985)
There is known a method which comprises using an adsorbent composed of zeolite with SiO.sub.2 /Al.sub.2 O.sub.3 molar ratios of 20-200 on which cuprous ion is carried as a process for removing CO from any mixed gas containing CO. (Refer to U.S. Pat. No. 4,019,879.)